The present disclosure relates to semiconductor devices having through electrodes, and manufacturing methods thereof.
In recent years, stacked semiconductor devices, which are formed by stacking a plurality of semiconductor chips on top of one another, have been developed to increase the performance of semiconductor devices and the integration level thereof. In many conventional stacked semiconductor devices, semiconductor chips are stacked on top of one another via relay substrates such as interposers, and are electrically connected by wire bonding. Such conventional stacked semiconductor devices have high interconnect resistance due to a long interconnect length, which limits an increase in operating speed. Moreover, the need to extend wires increases the overall size of the semiconductor devices, which limits reduction in size.
As a solution to these problems is proposed a method for connecting semiconductor chips via through electrodes. The through electrodes are formed by forming through holes in semiconductor chips and filling the through holes with a metal or a conductive resin. This configuration enables stacked semiconductor chips to be connected together with the smallest gap therebetween. This configuration can reduce the interconnect length, and thus the interconnect resistance as compared to the case where the semiconductor chips are connected by wire bonding, whereby the high speed operation can be achieved. Since this configuration does not require the region for extending the wires, the overall size of the stacked semiconductor device is determined only by the size of the semiconductor chips. The overall height of the stacked semiconductor device can also be reduced by thinning each semiconductor chip that is stacked. Thus, the overall size of the stacked semiconductor device can be reduced as compared to the conventional structures.
FIG. 21 is a cross-sectional view showing the structure around a through electrode in a conventional semiconductor device 300 disclosed in Japanese Published Patent Application No. 2005-12023. As shown in FIG. 21, a semiconductor substrate 301 of the semiconductor device 300 has a first surface 302a as a surface on which an integrated circuit is formed, and a second surface 302b that is opposite to the first surface 302a. A through electrode 305 is formed in the semiconductor substrate 301 so as to extend from the first surface 302a to the second surface 302b. An insulating film 308 is formed around an exposed portion of the through electrode 305 on the second surface 302b in order to electrically isolate the through electrode 305 from the semiconductor substrate 301. The semiconductor device 300 of FIG. 21 is manufactured by the following method.
First, an integrated circuit is formed over the first surface 302a of the semiconductor substrate 301, and a through hole is formed from the first surface 302a side to an intermediate depth in the semiconductor substrate 301. Note that an electrode 311 is formed on the first surface 302a of the semiconductor substrate 301 with an insulating film 303 therebetween, and a passivation film 310 is formed so as to cover the electrode 311. The through hole is formed so as to extend through the insulating film 303 and the electrode 311.
Next, an insulating film 304 is formed on the inner wall of the through hole from the first surface 302a side, and an outer layer portion 309, such as a barrier layer and a seed layer, is formed as appropriate on the insulating film 304. Thereafter, a conductive portion is buried in the through hole to form the through electrode 305. The through electrode 305 has a first protruding portion 307 that overlaps the electrode 311.
Then, the surface opposite to the first surface 302a of the semiconductor substrate 301 is subjected to mechanical polishing/grinding, chemical polishing/grinding, or the like in order to thin the semiconductor substrate 301 until the insulating film 304 at the bottom of the through electrode 305 is exposed. Subsequently, this opposite surface (the surface opposite to the first surface 302a of the semiconductor substrate 301) is etched by a known technique such as dry etching, wet etching, or the like to expose the bottom of the through electrode 305 having its sidewall covered by the insulating film 304. A second protruding portion 307 is formed in this manner.
Thereafter, the insulating film 308 is formed on the entire opposite surface (hereinafter referred to as the second surface 302b) other than the second protruding portion 307 of the through electrode 305. The insulating film 308 located on the sides of the second protruding portion 307 are removed by mechanical or chemical polishing/grinding, whereby the through electrode 305 is completed.